Study On Fish Species Diversity In The East China Sea In Autumn Based On Environmental DNA Technology

Biodiversity plays an important role in supporting the stability of ecosystems,and species diversity is the core of biodiversity.Traditional biodiversity surveys in the East China Sea are mainly bottom trawl surveys,which often cost a lot of manpower and material resources and damage the ecosystem.Environmental DNA technology refers to a research method for determining the distribution of target organisms in the environment by qualitative or quantitative analysis using PCR and sequencing technology after DNA fragments are directly extracted from environmental samples.In order to avoid the damage to biological system caused by the investigation,this non-aggressive investigation method will gradually become the mainstream of biological investigation.In this study,environmental DNA technology was used to analyze the diversity of fish species in the East China Sea in autumn.The main results are as follows:1.In the assessment of species diversity of environmental DNA fish in the East China Sea in autumn based on primer MiFish-E,the high-quality sequencing sequences from 14 stations ranged from 28 582 to 50 594,and 44 species of marine fish belonging to 2classes,23 orders,29 families,42 genera were obtained.Most of the species were found in the investigation of traditional fishery resources in the East China Sea,and more species were found in Clupeiformes and Scombriformes,8 species and 7 species respectively.The species with higher relative sequence abundance were Thryssa kammalensis,Scomberomorus niphonius,Scomber japonicus,Larimichthys polyactis and Mugil cephalus.The species with higher relative sequence abundance were not listed as dominant species in the historical traditional fishery resources survey.The number of fish species detected at each station varied significantly,ranging from 3 to 18.The alpha diversity among stations was significant difference,and generally showed high biodiversity at coastal stations and high biological abundance at offshore stations.2.In the assessment of species diversity of environmental DNA fish in the East China Sea in autumn based on primer MiFish-U,high-quality sequencing sequences from 14 stations ranged from 30 938 to 129 832,and 28 species of marine fish belonging to 2classes,15 orders,18 families,27 genera were detected,among which,the species of Clupeiformes was the most abundant,with 6 species in total.The species with higher relative sequence abundance were Muraenesox cinereus,Sardinops melanostictus,Scomber japonicus,Benthosema pterotum and Larimichthys polyactis.The difference in the number of fish species detected from each station was small,with the range of 13-17.The difference in alpha diversity among stations was small,and the species evenness was high.On the whole,the biological abundance was higher at the near-shore stations,while the biodiversity was higher at the offshore stations.3.Combining the results of the environmental DNA fish species in the East China Sea in autumn using primers MiFish-E and MiFish-U,56 species of marine fish belonging to 53 genera,27 orders,36 families and 2 classes were obtained.More high-quality sequences were obtained by the amplification products of primer MiFish-U,and the detection results of dominant species were more reliable.Primer MiFish-E was more capable of detecting cartilaginous fish,with a greater total number of species detected at the 14 stations.The fish species at the 14 stations in the East China Sea detected by primer MiFish-U had higher evenness and biodiversity,while the fish species at the 14 stations in the East China Sea detected by primer MiFish-E had higher abundance and wider distribution range of abundance index.The results showed that environmental DNA technology could be used as a supplement to traditional fishery resources investigation to rapidly detect the diversity and spatial distribution of fish species in the East China Sea.Its advantages of convenience,economy,high efficiency and non-destructive allowed it to have good application prospects in biodiversity research in typical epicontinental seas such as the East China Sea.At the same time,it was suggested that the station design with the same latitude and longitude should be added in the future investigation of fish species diversity in the East China Sea based on environmental DNA technology,and the day and night samples should be collected separately from the same station as far as possible,the sampling depth should be reasonably designed,and long-term monitoring should be conducted.